The invention relates to a reciprocating internal combustion engine, for example, in the form of an outboard engine for a boat.
An internal combustion engine acting as an outboard engine in a boat is known from publication EP 10 2012 015 907 B3, which includes two pistons working in a cylinder crank housing. Each piston is, by means of two connecting rods, coupled to two crankshafts rotating in opposite rotary directions. The crankshafts are disposed upright to the water line of the boat and influence a boat propeller for moving the boat. The internal combustion engine works according to the diesel process and has a diesel fuel injection system. A turbocharger device, which has an exhaust gas turbine and a compressor, is disposed at an upper end face of an internal combustion engine housing made up of a cylinder crank housing and a cylinder head. The latter is connected on the suction side of the internal combustion engine.
According to the publication, “A NEW CONCEPT FOR THE OUTBORD MARKET: Speech by Claus Brüstle on Oct. 8, 2013 at the 22nd Aachen Colloquium Automobile and Engine Technology,” the internal combustion engine therein described exhibits future-oriented, technical features and provides economic market opportunities. This internal combustion engine is based on the construction principle as illustrated in the known publication EP 10 2012 015 907 B3.
Publication DE 35 09 439 C2 describes a device for ventilating a crankcase of an internal combustion engine for separating oil from a mixture of oil and leaking gas. Via passageways and a space of a ventilation mechanism of the cylinder head, the mixture of oil and leaking gas reaches a first chamber of an oil separator. A second chamber connects to the first chamber, and a control valve is provided between the first chamber and the second chamber.
A gas outlet channel leads from the second chamber to an intake system of the internal combustion engine.
Publication DE 10 2006 038 831 A1 concerns an internal combustion engine recycling blow-by gases in a closed-loop system. For this purpose, blow-by gases, starting from a crankcase of the internal combustion engine, are fed into an intake system of the internal combustion engine via flow channels each operatively connected to one another and formed in a cylinder crank housing, a cylinder block, and a cylinder head.
It is an object of the present invention to optimize a reciprocating internal combustion engine, for example, in the form of an outboard engine for a boat, including at least one piston, which, via two connecting rods, works together with two parallel, in the opposite-direction-rotating crankshafts disposed in an upright manner in the boat, in such a manner that specific measures to a great extent reduce pollutants, which are caused by a mixture of oil and leaking gas resulting from operating the internal combustion engine in an internal combustion engine housing, in a targeted manner.
This object is achieved according to the present invention by a reciprocating internal combustion engine, comprising at least one piston, which is operatively connected by means of two connecting rods having two crankshafts rotating in opposite directions and running parallel to each other, which crankshafts are oriented in an upright manner to a horizontal water line of the boat, wherein an internal combustion engine housing of the internal combustion engine is made up of at least a cylinder crank housing and a cylinder head, having inlet and outlet valves, and is bounded by an upper end face and a bottom end face, wherein the internal combustion engine has a joint ventilation system with the internal combustion engine housing, which has an oil separating device provided with an oil pre-separator and a main oil separator, via which, when operating the internal combustion engine, a mixture of oil and leaking gas, resulting, for example, in a crankcase of the cylinder crank housing, reaches, by way of a discharge line extending adjacent to the upper end face, the oil pre-separator, from where said mixture of oil and leaking gas is led into the main oil separator and there is separated into the components of oil and leaking gas, which oil flows into an oil pan connecting at the bottom end face and which leaking gas flows near the upper end face into an intake system of the internal combustion engine.
The main advantages achieved by the present invention are that the internal combustion engine, designed as an outboard engine and having at least one piston and two upright crankshafts, has a ventilation system having a highly efficient oil pre-separator and a main oil separator. They significantly contribute to protecting the environment, especially when using the outboard engine for boats in flowing and standing water. When operating the internal combustion engine, the mixture of oil and leaking gas, resulting, for example, in a crankcase, is led in a particularly efficient manner through said oil separator device and is separated into the components, that is, into oil and leaking gas. In this instance, the oil is fed to the oil pan and the leaking gas is fed into the intake system of the internal combustion engine. The mixture of oil and leaking gas is transported via the discharge line situated adjacent to the upper end face from the crankcase of the cylinder crank housing into the oil pre-separator, and, in order to simplify the architecture, the discharge line is placed at the outside of the internal combustion engine housing alongside the upper end face.
The function of the ventilation system or the oil separator device is expanded in that the mixture of oil and leaking gas is brought from the valve-camshaft area of the cylinder head into the oil pre-separator and the main oil separator via a first passageway. It is demonstrated in an exemplary manner that the oil pre-separator is provided with at least first and second upright guiding chambers separated by a guiding element, in which, in order to through-flow the mixture of oil and leaking gas, a second passageway is incorporated between the chambers adjacent to the bottom end face of the chamber of the internal combustion engine. An advantageous embodiment of the oil pre-separator is achieved when the mixture of oil and leaking gas in the first guiding channel is guided from the top to the bottom between the upper end face and the bottom end face alongside the guiding element and enters the second guiding chamber through the second passageway, via which said mixture of oil and leaking gas flows in the direction of the upper end face and from there reaches the main oil separator by inter-positioning a third passageway.
Measures are established when the oil pre-separator and the main oil separator are combined into a housing structure and when at least housing parts of the housing structure are mounted by means of holding screws to the cylinder head of the internal combustion engine housing. In this instance, it is to be additionally highlighted that the oil pre-separator and the main oil separator are put together by inter-positioning an annular spacer in such a manner that connecting planes run between the oil pre-separator and the spacer and between the spacer and the main oil separator and that the oil pre-separator, the spacer and the main oil separator are connected to one another by one or a plurality of connecting screws, which connecting screws adjacent to a rim zone of the housing structure are acting approximately perpendicular to the connecting planes. The design advantageously implements that the main oil separator is designed as a type of hood of the housing structure, which is led up to the spacer by a circumferential connecting rim.
A superior architecture is achieved in that the oil separator is provided with a labyrinth, along which the mixture of oil and leaking gas is guided, as a result of which the gas is, on one hand, separated in the direction of the intake system and, on the other, the oil in the direction of the oil pan. This is also supported in that the labyrinth has guide webs disposed at a distance from one another, which, starting from first and second upright, opposite sides, interlock in an alternating manner and which are situated in such a manner that separated oil of the mixture of oil and leaking gas is guided into recycling ducts in the direction of the oil pan. Finally, a well thought-through and simple construction is achieved, if the guide webs of the labyrinth are mounted at the inside of the hood of the main oil separator.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.